1. Field of the Invention
The invention is related to an electronic device, and more particularly to a thin film transistor and a pixel structure.
2. Description of Related Art
With the development of display technology, high-resolution display panels have become mainstream in display products nowadays. To fabricate a display panel having high resolution, the area occupied by each pixel structure needs to be reduced, and in consideration of the transmittance of the display panel, the area in each pixel structure occupied by a thin film transistor needs to be as small as possible, so as to enhance an aperture ratio of the display panel.
In conventional technology, the thin film transistor is disposed on a substrate and includes a gate, a channel, a stopper layer covering the channel, a source and a drain, wherein the stopper layer is for protecting the channel, so that the channel is not easily damaged in the process of etching a conductive layer to form the source and the drain. In terms of the types of patterns, the stopper layer is divided into a nearly-complete coverage type and an island-coverage type. A nearly-complete coverage stopper layer is to dispose two independent contact holes merely at two spots corresponding to the source and the drain, so that the source and the drain are filled in the two contact holes and electrically connected to the channel; at other spots, the nearly-complete coverage stopper layer nearly completely covers the whole substrate. The disadvantage of the thin film transistor adopting the nearly-complete coverage stopper layer is that the area corresponding to the two independent contact holes needs to be reserved on the channel, which makes it difficult to reduce the area occupied by the channel (or the area occupied by the thin film transistor). The island-coverage stopper layer is to dispose an island-shaped stopper pattern merely above the corresponding channel center without any stopper pattern in other spots. The disadvantage of the thin film transistor adopting the island-coverage stopper layer is that in the process of etching an insulated layer for forming the island-shaped stopper pattern, since the area of the insulated layer to be removed is larger, the processing time for forming the island-shaped stopper pattern is long and processing parameters are not easily adjusted, which leads easily to the issue that the whole insulated layer is removed without forming the island-shaped stopper layer.